Sectional boiler construction



Nov. 2, 1965 J. G. MUELLER SECTIONAL BOILER CONSTRUCTION 3 SheetsSheet 1 Filed Aug. 8, 1963 INVENTOR. JOHANNES G. MUELLER 7W, yaw

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Nov. 2, 1965 J. G. MUELLER I SECTIONAL BOILER CONSTRUCTION 3 Sheets-Sheet 2 Filed Aug. 8, 1963 H mm mu 0A z m J W w G W S E. N M 7 H 7 i W Nov. 2, 1965 J. G. MUELLER 3,

SECTIONAL BOILER CONSTRUCTION Filed Aug. 8, 1965 3 Sheets-Sheet 3 PLATE wm4 PROGRESSIVE PORT ARRANGEMENT 7 4- 2. l 7L FLUE PASSAGES 25p U U l: [i /Z 5 INVENTOR. JOHANNES G-MUELLEQ United States Patent 3,215,125 SECTIONAL BOILER CONSTRUCTION Johannes G. Mueller, Michigan City, Ind., assignor to Weil-McLain Company, Inc., Michigan City, Ind., a corporation of Indiana Filed Aug. 8, 1963, Ser. No. 300,898 8 Claims. (Cl. 122-225) The present invention relates to heating equipment and, more specifically, to a boiler construction utilizable with forced or natural draft firing.

In general, this invention is concerned with improvements in the internal construction of boilers which allows for increased etficiency in operation by providing for more uniform distribution throughout the boiler passages of the gaseous combustion products and, in connection with forced draft fired boilers, by providing a positive seal against gas leakage through the boiler walls. These improvements are applicable to small boilers, for example, domestic size boilers as well as large boilers utilized in heating plants for large buildings.

A primary object of the present invention is to provide improved internal construction for boilers wherein flue gas produced by combustion which is confined to one end of the boiler, is uniformly distributed along the entire length of the boiler. A related object is to provide means for insuring that all boiler sections of a sectional boiler contribute equally in the transfer of heat by controlling flow of flue gas in a pattern such as to provide for optimum heat transfer. Additionally, an object is to provide such a boiler wherein the flow controlling means is adjustable so that flue gas flow is regulatable.

Another primary object of the present invention is to provide an improved internal construction for sectional type boilers wherein a positive and permanent seal is provided against gas leakage. An allied object is to provide an improved seal for sectional type boilers which allows for improved operation of the boiler when forced draft fired as well as natural draft fired.

An additional object is to provide an improved sectional type boiler wherein the boiler sections define a firebox completely surrounded by water-backed heating surfaces so that no combustion chamber is required. Accordingly, a related object is to provide an improved boiler construction which protects against heat less through the bottom of the boiler.

A more specific object is to provide an improved boiler construction for use with a flame retention type burner wherein the flow of flue gas is regulated such that resistance to flow decreases progressively from the front to the rear of the boiler in a direction away from the burner. Another more specific object is to provide an improved boiler construction for use with a natural fired burner wherein the flow of flue gas is regulated such that resistance to flow increases progressively from the front to the rear of the boiler in a direction away from the burner. A related object is to provide an improved boiler construction which may be adapted for use with a forced draft type burner or a natural draft type burner so that the desired resistance to flow pattern is provided for the burner used.

Still another more specific object of the present invention is to provide an improved sectional type boiler construction wherein the boiler sections define a firebox and means are provided for positively sealing adjacent sections entirely around the firebox. A collateral object is to provide such an improved boiler construction wherein the sealing means is accessible once the boiler has been erected.

A general object of the present invention is to provide a new and improved sectional boiler wherein the construction thereof facilitates erection, use and maintenance. A related object is to provide a sectional boiler construction which may be readily dismantled. Another general object is to provide a more compact boiler.

Further, a general object is to provide a new and improved sectional boiler characterized in its increased efficiency of operation.

Other objects and advantages of the invention will become apparent as the following description proceeds, taken on-conjunction with the drawings, in which:

FIGURE 1 is a perspective view of an erected sectional type boiler embodying the present invention wherein parts are broken away to illustrate the internal constructional details of the boiler;

FIGS. 2, 3 and 4 are front elevated views of the front intermediate and back sections respectively of boiler sections utilizable in FIG. 1 constructed in accordance with one embodiment of the present invention;

FIG. 5 illustrates the relationship between flue passages of the boiler in FIG. 1 and means for regulating the flow of flue gas therethrough;

FIG. 6 is a front elevated view of a front section for the boiler in FIG. 1 constructed in accordance with a second embodiment of the present invention;

FIG. 7 is a front elevated view of a front section for the boiler in FIG. 1 constructed in accordance with a third embodiment of the present invention; and

FIG. 8 is a partial, cut away view illustrating the cross sectional relationship of the sealing means with two of the sections illustrated in FIG. 1.

While the invention has been described in connection with certain preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, the invention is intended to cover the various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

For the purpose of describing a preferred environment for the present invention, it is shown embodied in a sectional type boiler, that is, a boiler unit made up of a plurality of individual rectangular shaped sections which are fastened together by mechanical devices and which define a firebox located centrally in the lower portion thereof.

Referring to the drawings and more specifically to FIG. 1, a sectional type boiler 10, wherein the present invention is incorporated, is illustrated having the front portion thereof removed. In the illustrated embodiment, rectangular boiler sections 11 are erected so as to define a firebox 12 located centrally thereof in the lowermost portion. For the purpose of firing the boiler, a forced draft type burner or a natural draft fired burner (not shown) may be mounted in place on the front of the boiler adjacent the firebox 12. Hot flue gases are produced by flame in the firebox and pass through the boiler to a smoke collar (not shown) which serves to lead the gases to the chimney. The smoke collar is fastened on the back section of the boiler and receives flue gases from a collector chamber constructed as horizontal flue galleries 15, the collector chamber being in communication with the smoke collar through a smoke opening in the outer wall of the back section casting. Additionally, hinged doors (not shown) are mounted adjacent the collector chamber for sealing off the chamber and for allowing access thereto, for example, to clean out the chamber.

For the purpose of generating steam or supplying heated water to a hot water system, water is circulated through an internal header 16 and through water passages 17 formed by coring the castings for each boiler section. The internal header 16 is formed by connecting upper nipple openings 18 by slip nipples 19, and a pipe (not shown) which is connected to the header extends to the heating system. As will be observed from a careful examination of FIG. 1, the individual sections of the boiler are cast so as to form the water passages 17 within each individual section and the firebox 12 is entirely surrounded by such Water passages, i.e., the firebox is surrounded by water-backed surfaces. Since the firebox is surrounded by water-backed surfaces, a combustion chamber is not required as would otherwise be required. Accordingly, this boiler construct-ion allows for reduction in the boiler height and thus allows for a more compact boiler. This construction also reduces heat loss through the bottom of the boiler.

The boiler sections are also constructed so as to provide vertical passages or uptakes 21 between adjacent boiler sections. For this purpose, each side of the individual boiler sections is formed so that, when adjacent sections are connected together, vertical uptake passages 21 are left between the sections and both sides of the boiler. As will become apparent, the uptakes 21 are connected to the horizontal flue galleries 15 (collector chamber) which, in this embodiment, are centrally located in the boiler above the firebox 12.

For transferring heat to the water circulating through the header 16 and the water passages 17 in the sections 'of the boiler, the flue gases produced in the firebox by natural or forced draft firing are forced laterally toward the outer wall of the boiler to pass upwardly between the adjacent boiler sections through the vertical uptake passages 21. As may be seen by reference to FIG. 1, these uptake passages open in their lower part to the upper region of the firebox crown 22. The vertical limits of the uptake passages 21 are defined by the rounded upper corners of the boiler itself, which form turn-around passages 21'. These passages 21' are disposed laterally of the horizontal flue gas galleries 15 with which they communicate by means of downwardly directed connecting passages 21" so that the hot flue gases pass via the turn-around passages to the collector chamber after flowing through the vertical uptakes. Since a vertical uptake is formed at each side and between adjacent sections of the boiler, the hot flue gases in the firebox are divided into a plurality of individual streams of gases equal in number to the number of uptakes and these streams of gases flow into the horizontal flue galleries 15.

In accordance with a principal feature of the present invention, means are provided for controlling the flow of flue gases in the uptake passages 21 so that a uniform distribution of the flue gas along the length of the boiler is obtained. Morespecifically, means are provided for insuring that all boiler sections. contribute equally in the transfer of heat to the heating surfaces by controlling the flow of flue gases in a pattern such .as to provide for optimum heat transfer. Still more specifically, means are provided which may :be adapted for controlling the flow of flue gases when the boiler is used inconjunction with forced draft firing (flame retention type burners) or natural draftfiring (natural fired burners).

For this purpose, reference is made to FIGS. 1-4 wherein slidable plates or baffles 25 having flue gas ports 25a formed therein are horizontally disposed between the downwardly directed passages 21" and the horizontal flue galleries 15, the plates 25 extending the length of the boiler. The ports 25a progressively increase in size along the length of the plate 25 and the plates may be positioned so that the resistance to the flow of flue gas in the associated passages is progressively decreased along the length of the plate. Thus, the plates 25 are disposed between horizontal collector passages 26 joining the downwardly directed passages 21" and the horizontal flue galleries 15, such that flue gas received from the vertical uptakes flows horizontally above the plates for dispersion along the boiler as well as vertically downwardly through the ports therein.

With forced draft firing using a flame retention type burner, the flame is substantially confined to the front end of the boiler in the region of the burner nozzle. Accordingly, with forced draft firing, the means for controlling flow of flue gases through the uptake passages 21 is disposed within the boiler so as to provide progressive 1y decreasing resistance to the flow of flue gas as between successive uptake passages from the front of the boiler to the rear thereof, i.e., in a direction away from the burner whereby the gases are tended to be drawn toward the rear of the boiler. Conversely, with natural draft firing using a conventional burner, the flame extends along the firebox and into the end of the boiler removed from the burner. Accordingly, with natural draft firing, the flue gas regulating means is so disposed in the boiler that it provides for progressively increasing resistance to the flow of flue gases as between successive uptake passages from the front of the boiler to the rear thereof, i.e., in a direction away from the burner, whereby gases are tended to be drawn toward the front of the boiler. It follows that the effect of the flue gas regulating means is to force a greater portion of the flue gases produced in the firebox through the paths of least resistance so that balanced, horizontal flue gas travel is provided, i.e, equal amounts of flue gas flow through the various uptake passages throughout the entire length of the boiler.

In keeping with the present invention, the slide plates or baffles 25 are reversible. Thus, the slide plates may be disposed in the boiler so that the ports either progressively increase or progressively decrease in size from the front of the boiler to the rear thereof. Accordingly, the boiler may be adapted for use with either forced or natural draft firing of the boiler.

Referring to FIG. 5, the relationship between the ports 25a in the slide plate 25 and the flue gas passages 21" is illustrated, the slide plates and the passages being illustrated in the same plane for simplicity whereas in actual practice they are disposed in perpendicular planes so that the ports adjustably restrict flow through the passages. As may be seen the width of the smallest port is equal to the width, f, of the flue passages 21" and the widths of the succeeding ports progressively increase by increments of when n equals the total number of ports. In the illustrated embodiment, the width of the largest port may be determined by the following expression:

wherein p equals the width of the individual slot; 11 equals the number of flue passages and, thus, the number of the slots which are progressively numbered; and 7 equals the width of the flue passage 21". Additionally, the spacing between the slots, R, is preferably determined by the following equation:

wherein S equals the width of each section 11. Finally, the width, W, of the Water pasages 17 is preferably greater than two times the width of the flue passages 21". However, it is to be understood that the invention is not to be limited to the above-mentioned relationships which are exemplary of the preferred construction.

Utilizing the relationship between the slide plate 25 and the flue passages 21" illustrated in FIG. 5, it will be apparent that the first flue passage is completely blocked by the slide plate and that the portion of each subsequent passage (from right to left) blocked by the slide plate progressively decreases. Accordingly, the resistance to flue gas flow in the flue passages 21" progressively decreases from right to left. If the slide plate 25 is moved in successive increments to the right, it will be apparent that the resistance to flow in each flue passage will be decreased and that successive ones of the passages from left to right will be sequentially rendered completely open until all passages are open. Thus, any desired relationship of resistance to flow of flue gases in successive ones of the passages 21" may be obtained by positioning the slide plate 25.

In view of the foregoing, it will be apparent that, as the slide 25 in FIG. 5 is moved to the left, a condition will be reached whereat all of the passages 21" are completely closed. However, in such boilers, it is not desirable for the flow of gases to be completely blocked. To avoid this condition, in keeping with the invention, a bypass is provided for the flue gases, herein shown as a turn-around passage 27 in FIG. 1, between the horizontal passages 26 and the galleries at the front of the boiler which is not affected by the slide and allows for the flow of flue gas therethrough (as indicated by the arrow) to the flue galleries 15 when the passages 21" are all blocked off.

As mentioned above, the resistance to flue gas flow offered by the restricted ports 25a progressively decreases from right to left as illustrated in FIG. 5. Conversely, if the slide plate 25 is reversed, the resistance of gas flow will progressively increase from left to right.

While the slide plates 25 are shown in FIG. 2 in a boiler with laterally disposed vertical uptakes wherein the plates are horizontally mounted over the firebox at the entrance to the horizontal flue galleries 15, other mounting arrangements have been found suitable. One such alternative mounting arrangement is shown in FIG. 6 wherein the slide plates 25 are vertically rather than horizontally disposed. Referring to FIG. 6, an elevation of a front section corresponding to the front section illustrated in FIG. 2 is shown wherein the flue gases in this arrangement are also forced laterally toward the outer wall of the boiler to pass upwardly between the individual boiler sections through vertical uptake passages. The vertical limits of the uptake passages are defined by the rounded upper corners of the boiler, which form turnaround passages 21'. The passages 21 are disposed above horizontal flue gas galleries 15 which are defined by the adjacent sections and are connected thereto through downwardly directed passages 21", such passages 21" being interconnected by openings 26 defining horizontal passages 26 in the boiler. T=he flue galleries 15 in turn communicate with the smoke collar and the chimney. In operation, flue gases pass up the passage 21 around passage 21 down passage 21" and through the ports in the vertically disposed slide plate 25 to the gas galleries 15, the relationship between the passages 21" and the slide plate 25 corresponding to that illustrated in FIG. 5.

Intermediate and rear sections to complete a boiler with a front section like that shown in FIG. 6 have not been illustrated. However, as will be apparent to those skilled in the art, the intermediate and rear sections will correspond to the intermediate and rear sections illustrated in FIGS. 3 and 4, but will be constructed in a similar manner to the front section illustrated in FIG. 6 so that the slide plates 25 are vertically disposed in the boiler.

It is further contemplated that the flow controlling means of the present invention is suited for boilers having different flue gas passage arrangements. A slide plate construction and mounting for boiler sections having flue gas uptakes 21 located generally in the central region of the sections above the firebox 12 and the horizontal flue gas galleries 15 laterally disposed outwardly from the uptakes, is shown in FIG. 7. It will be seen that the uptakes 21 located generally in the central region are connected through turn-around passages 21 and downwardly directed passages 21" to the flue gas galleries 15 through vertically disposed slide plates 25. In this arrangement, the downwardly directed passages 21" are laterally disposed adjacent the outer surfaces of the boiler sections. In operation, gaseous combustion products pass up 6 through the vertical uptakes 21 around the turn-around passages 21' down the passages 21" and through the ports in the slide plates 25 to the flue galleries 15, the relationship between passages 21" and the plates 25 corresponding to that illustrated in FIG. 5.

Again, intermediate and rear sections of this arrangement have not been illustrated. However, it will be apparent to those skilled in the art that such sections will be provided with gas flow passages corresponding to the passages of the front section illustrated in FIG. 7.

In accordance with another aspect of the present invention, adjacent sections of the boiler are positively and permanently gas-tight sealed. More specifically, the boiler sections are sealed therebetween such that the interior of the boiler may be maintained under positive pressure, as with forced draft firing, without leakage of gases from the boiler interior into the surrounding space. Such sealing is also important for natural draft firing since uncontrolled air leakage into the boiler which might impair uniform flue gas distribution is eliminated throughout the life of the boiler so as to assure high efficiency of operation. In carrying out this aspect of the invention as shown in FIGS. 2-4, the boiler sections are cast with sealing lands 30 provided around the outer edge thereof so as to form a substantially continuous loop around the firebox. Preferably, the sealing lands extend around the periphery of the upper portion of each section and extend laterally along the portion of each section which defines the lower surface of the firebox. With such an arrangement, it will be apparent that the sealing lands are accessible even after the boiler has been assembled. Additionally, these sections are cast with sealing lands 31 and 32 centraly formed about the collector chamber or flue galleries 15 thereby separating this region of the boiler from the other regions thereof. When two of the boiler sections are moved into abutting relationship, the sealing lands thereon will be moved into register so that a seal is provided which extends in a continuous loop around the chambers and gas passages of the boiler.

So as to provide an air and gas-tight seal between registering lands on adjacent sections of the boiler and thus for the purpose of effectively sealing between every section of the boiler, the sealing lands are grooved or channeled for receiving sealing material herein shown as heat resistant flexible rope 35, such as asbestos rope or the like. A continuous length of rope is laid in the grooves or channels 36 for-med in the sealing lands 30 so that the ends thereof overlap and a continuous seal is provided around the entire boiler interior. Similarily, a length of rope is laid in the grooves 37 and 38 of the lands 31 and 32. It is preferred that the asbestos rope should be glued in place in the curved sealing grooves, using adhesive (see FIG. 8). As will be readily appreciated, this also facilitates erection of the boiler because the asbestos rope is held in place. To insure that the sealing material remains intact upon dismantling of the boiler, the adhesive should be applied only to one side of the asbestos rope in the grooved lands of one section of the boiler.

In the erection of the boiler shown as exemplary in the drawings, a slip-nipple 19 is installed in the upper slipnipple opening 18 of one section, for example, the front section illustrated in FIG. 2, to form the internal header 16. Smaller, lower nipple openings 40 are then conditioned for receipt of lower nipples 41 which are pounded in place to form a part of the water passage system of the boiler. After the asbestos rope has been placed on the one section, for example, a front section as illustrated in FIG. 2, the upper and lower nipple openings of a second section, for example, an intermediate section as illustrated in FIG. 3, are then prepared for receiving the nipples. The intermediate section is then driven against the front section with a heavy mallet or the like to start the nipples into the lower openings and into the upper ports or openings of that section. At this point, draw rods 45 are assembled on the sides of the boiler and the intermediate section is then connected by means of these draw rods .to the front section. The remaining sections, i.e., intermediate and rear sections, are then assembled in place following the same sequence of steps.

For insuring a perfect seal between boiler sections, it is desirable that the grooved or channeled sealing lands 30 constructed in the outer wall of the boiler be fashioned so that, during the operation of drawing the adjacent sections of the boiler together by means of the draw rods, the asbestos rope 35 in the outer curved sealing groove will be compressed so as to form a relatively denser flue gas impervious bead toward the inside of the boiler. For this purpose, the meeting lands 30 are so formed that when the boiler sections are drawn fully together, to the position shown in FIG. 8, the gap 50 separating the inside edges 51 and 52 of the boiler sections is smaller than the gap 53 separating the outside edegs 54 and 55. The draw rods 45, when drawing the adjacent boiler sections together, act to compress the asbestos rope 35 and actually extrude it into the gaps 50 and 53 separating the sections. By providing a larger space toward the outside edge of the outer wall of the sections, however, the compressed asbestos rope is allowed to escape somewhat, providing compression relief, while the portion of asbestos rope toward the inside of the boiler is made denser and gas impervious.

In view of the foregoing, it will be seen that the invention provides a sectional boiler construction with sealing means between sections fully enclosing the boiler interior, which, due to such sealing, can be operated with either forced draft or natural draft firing and in which under either mode of operation the gaseous products of combustion are uniformly distributed throughout the entire length of the boiler and thus are dispersed to all of the water-backed flue gas passages for efficient heat transfer.

I claim as my invention:

1. In a boiler adapted to be erected so as to define a firebox, the combination which comprises, fully enclosed uptakes extending from the firebox vertically for receiving shares of flue gas produced in the firebox, the uptakes being regular in cross section and extending uninterruptedly from the firebox to the top of the boiler, a horizontal collector chamber extending the length of the boiler for receiving the streams of flue gas from the uptakes, means providing turn-around connecting passages associated with the uptakes through which the flue gas flows to the collector chamber, a slidable damper member having ports formed along the length thereof disposed between the turn-around connecting passages and the collector chamber for regulating the flow of flue gas through the uptakes to the collector chamber, and means including a bypass passage connecting the turn-around passages to the collector chamber to permit the flow of flue gas therebetween when the damper member is in a position to prohibit such flow.

2. In a boiler adapted to be erected so as to define a firebox, the combination which comprises, fully enclosed uptakes disposed laterally and extending from the firebox vertically for receiving shares of flue gas produced in the firebox, the uptakes being regular in cross section and extending uninterruptedly from the firebox to the top of the boiler, a horizontal collector chamber extending the length of the boiler for receiving the streams of flue gas from the uptakes, means providing turn-around connecting passages associated with the uptakes through which the flue gas flows to the collector chamber, and a slidable damper member disposed between the turn around connecting passages and the collector chamber for regulating the resistance to flow therebetween so that a uniform distribution of flue gas flow along the length of the boiler may be obtained, the damper member having ports formed along the length thereof which cooperate with the turn-around connecting passages, the width of the port at one end being equal to the width of the turnaround passages and the widths of the succeeding ports progressively increasing so that the damper member may be positioned such that the resistance to flow decreases progressively from one end of the boiler to the other according to a desired pattern.

3. In a boiler adapted to be erected so as to define a firebox, the combination which comprises, fully enclosed uptakes disposed laterally and extending from the firebox vertically for receiving shares of the gas produced in the firebox, the uptakes being regular in cross section and extending uninterruptedly from the firebox to the top of the boiler, a horizontal collector chamber extending the length of the boiler for receiving the streams of flue gas from the uptakes, means providing turnaround connecting passages associated with the uptakes through which the flue gas flows to the collector chamber, and a slidable and reversible damper member disposed between the turn-around connecting passages and the collector chamber for regulating the resistance to flow therebetween so that a uniform distribution of flue gas flow along the length of the boiler is obtained, the damper member having ports formed therein along the length thereof which cooperate with the turn-around connecting passages, the width of the ports progressively increasing from one end to the other so that the damper member may be preset such that the resistance to flow decreases progressively from one end of the boiler to the other according to a desired pattern.

4. In a sectional boiler having a plurality of spaced sections and adapted to be erected so as to define a firebox, the combination comprising, sealing means provided in facing surfaces of adjacent boiler sections which register and which are formed in continuous loops around the firebox, means for tying the sections together, fully enclosed uptakes extending from the firebox vertically between the adjacent boiler sections for receiving shares of the flue gas produced in the firebox, the uptakes being regular in cross-section and extending uninterruptedly from the firebox to the top of the boiler, a horizontal collector chamber extending the length of the boiler for receiving the streams of flue gas from the uptakes, means providing turn-around connecting passages associated with the uptakes through which the flue gas flows to the collector chamber, sealing means provided in facing surfaces of adjacent boiler sections which register and which are formed to seal 01f the horizontal collector chamber from the firebox and the uptake passages, an adjustable and reversible damper member having ports along the length thereof disposed between turn-around connecting passages and the collector chamber for regulating the flow of flue gas through the uptakes to the collector chamber, the width of the port at one end being equal to the width of the turn-around passages and the widths of the succeeding ports progressively increasing by increments of l/n X1, where 1 equals the width of the turn-around passages and n equals the number of ports so that the damper member may be positioned to decrease the resistance to flow progressively from one end of the boiler to the other according to a desired pattern.

5. A boiler as claimed in claim 2 wherein said collector chamber is centrally located above the firebox and below the upper termini of the uptakes and said damper member being vertically disposed between the turnaround passages and the collector chamber.

6. A boiler according to claim 2 wherein said collector chamber is centrally located above the firebox and below the upper termini of the uptakes and said damper member being horizontally disposed between the turn-around passages and the collector chamber.

7. A boiler as claimed in claim 2 wherein said collector chamber is located outwardly from the firebox toward the boiler sidewalls and said damper member being disposed vertically between the connecting passages and the collector chamber,

9 8. A boiler according to claim 2 wherein the Widths of said succeeding ports progressively increase by increments of 1/n f, Where f equals the width of the turnaround passages and n equals the number of ports.

References Cited by the Examiner UNITED STATES PATENTS 554,872 2/96 Hersey 122-226 1,147,643 7/15 Reed 122135 2,206,398 7/40 Grimm 122-225 X 1 10 Livar 122--225 De Vries 11098 Goodgion 11097 Martin 11072 Mueller 122231 X FREDERICK L. MATTESON, JR., Primary Examiner. KENNETH W. SPRAGUE, PERCY L. PATRICK,

Examiners. 

1. IN A BOILER ADAPTED TO BE ERECTED SO AS TO DEFINE A FIREBOX, THE COMBINATION WHICH COMPRISES, FULLY ENCLOSED UPTAKES EXTENDING FROM THE FIREBOX VERTICALLY FOR RECEIVING SHARES OF FLUE GAS PRODUCED IN THE FIREBOX, THE UPTAKES BEING REGULAR IN CROSS SECTION AND EXTENDING UNINTERRUPTEDLY FROM THE FIREBOX TO THE TOP OF THE BOILER, A HORIZONTAL COLLECTOR CHAMBER EXTENDING THE LENGTH OF THE BOILER FOR RECEIVING THE STREAMS OF FLUE GAS FROM THE UPTAKES, MEANS PROVIDING TURN-AROUND CONNECTING PASSAGES ASSOCIATED WITH THE UPTAKES THROUGH WHICH THE FLUE GAS FLOWS TO THE COLLECTOR CHAMBER, A SLIDABLE DAMPER MEMBER HAVING PORTS FORMED ALONG THE LENGTH THEREOF DISPOSED BETWEEN THE TURN-AROUND CONNECTING PASSAGES AND THE COLLECTOR CHAMBER FOR REGULATING THE FLOW OF FLUE GAS THROUGH THE UPTAKES TO THE COLLECTOR CHAMBER, AND MEANS INCLUDING A BYPASS PASSAGE CONNECTING THE TURN-AROUND PASSAGE STO THE COLLECTOR CHAMBER TO PERMIT THE FLOW OF FLUE GAS THEREBETWEEN WHEN THE DAMPER MEMBER IS IN A POSITION TO PROHIBIT SUCH FLOW. 